| 1 | /* A splay-tree datatype. |
| 2 | Copyright (C) 1998, 1999 Free Software Foundation, Inc. |
| 3 | Contributed by Mark Mitchell (mark@markmitchell.com). |
| 4 | |
| 5 | This file is part of GNU CC. |
| 6 | |
| 7 | GNU CC is free software; you can redistribute it and/or modify it |
| 8 | under the terms of the GNU General Public License as published by |
| 9 | the Free Software Foundation; either version 2, or (at your option) |
| 10 | any later version. |
| 11 | |
| 12 | GNU CC is distributed in the hope that it will be useful, but |
| 13 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 15 | General Public License for more details. |
| 16 | |
| 17 | You should have received a copy of the GNU General Public License |
| 18 | along with GNU CC; see the file COPYING. If not, write to |
| 19 | the Free Software Foundation, 59 Temple Place - Suite 330, |
| 20 | Boston, MA 02111-1307, USA. */ |
| 21 | |
| 22 | /* For an easily readable description of splay-trees, see: |
| 23 | |
| 24 | Lewis, Harry R. and Denenberg, Larry. Data Structures and Their |
| 25 | Algorithms. Harper-Collins, Inc. 1991. */ |
| 26 | |
| 27 | #ifdef HAVE_CONFIG_H |
| 28 | #include "config.h" |
| 29 | #endif |
| 30 | |
| 31 | #ifdef HAVE_STDLIB_H |
| 32 | #include <stdlib.h> |
| 33 | #endif |
| 34 | |
| 35 | #include "libiberty.h" |
| 36 | #include "splay-tree.h" |
| 37 | |
| 38 | static void splay_tree_delete_helper PARAMS((splay_tree, |
| 39 | splay_tree_node)); |
| 40 | static void splay_tree_splay PARAMS((splay_tree, |
| 41 | splay_tree_key)); |
| 42 | static splay_tree_node splay_tree_splay_helper |
| 43 | PARAMS((splay_tree, |
| 44 | splay_tree_key, |
| 45 | splay_tree_node*, |
| 46 | splay_tree_node*, |
| 47 | splay_tree_node*)); |
| 48 | static int splay_tree_foreach_helper PARAMS((splay_tree, |
| 49 | splay_tree_node, |
| 50 | splay_tree_foreach_fn, |
| 51 | void*)); |
| 52 | |
| 53 | /* Deallocate NODE (a member of SP), and all its sub-trees. */ |
| 54 | |
| 55 | static void |
| 56 | splay_tree_delete_helper (sp, node) |
| 57 | splay_tree sp; |
| 58 | splay_tree_node node; |
| 59 | { |
| 60 | if (!node) |
| 61 | return; |
| 62 | |
| 63 | splay_tree_delete_helper (sp, node->left); |
| 64 | splay_tree_delete_helper (sp, node->right); |
| 65 | |
| 66 | if (sp->delete_key) |
| 67 | (*sp->delete_key)(node->key); |
| 68 | if (sp->delete_value) |
| 69 | (*sp->delete_value)(node->value); |
| 70 | |
| 71 | free ((char*) node); |
| 72 | } |
| 73 | |
| 74 | /* Help splay SP around KEY. PARENT and GRANDPARENT are the parent |
| 75 | and grandparent, respectively, of NODE. */ |
| 76 | |
| 77 | static splay_tree_node |
| 78 | splay_tree_splay_helper (sp, key, node, parent, grandparent) |
| 79 | splay_tree sp; |
| 80 | splay_tree_key key; |
| 81 | splay_tree_node *node; |
| 82 | splay_tree_node *parent; |
| 83 | splay_tree_node *grandparent; |
| 84 | { |
| 85 | splay_tree_node *next; |
| 86 | splay_tree_node n; |
| 87 | int comparison; |
| 88 | |
| 89 | n = *node; |
| 90 | |
| 91 | if (!n) |
| 92 | return *parent; |
| 93 | |
| 94 | comparison = (*sp->comp) (key, n->key); |
| 95 | |
| 96 | if (comparison == 0) |
| 97 | /* We've found the target. */ |
| 98 | next = 0; |
| 99 | else if (comparison < 0) |
| 100 | /* The target is to the left. */ |
| 101 | next = &n->left; |
| 102 | else |
| 103 | /* The target is to the right. */ |
| 104 | next = &n->right; |
| 105 | |
| 106 | if (next) |
| 107 | { |
| 108 | /* Continue down the tree. */ |
| 109 | n = splay_tree_splay_helper (sp, key, next, node, parent); |
| 110 | |
| 111 | /* The recursive call will change the place to which NODE |
| 112 | points. */ |
| 113 | if (*node != n) |
| 114 | return n; |
| 115 | } |
| 116 | |
| 117 | if (!parent) |
| 118 | /* NODE is the root. We are done. */ |
| 119 | return n; |
| 120 | |
| 121 | /* First, handle the case where there is no grandparent (i.e., |
| 122 | *PARENT is the root of the tree.) */ |
| 123 | if (!grandparent) |
| 124 | { |
| 125 | if (n == (*parent)->left) |
| 126 | { |
| 127 | *node = n->right; |
| 128 | n->right = *parent; |
| 129 | } |
| 130 | else |
| 131 | { |
| 132 | *node = n->left; |
| 133 | n->left = *parent; |
| 134 | } |
| 135 | *parent = n; |
| 136 | return n; |
| 137 | } |
| 138 | |
| 139 | /* Next handle the cases where both N and *PARENT are left children, |
| 140 | or where both are right children. */ |
| 141 | if (n == (*parent)->left && *parent == (*grandparent)->left) |
| 142 | { |
| 143 | splay_tree_node p = *parent; |
| 144 | |
| 145 | (*grandparent)->left = p->right; |
| 146 | p->right = *grandparent; |
| 147 | p->left = n->right; |
| 148 | n->right = p; |
| 149 | *grandparent = n; |
| 150 | return n; |
| 151 | } |
| 152 | else if (n == (*parent)->right && *parent == (*grandparent)->right) |
| 153 | { |
| 154 | splay_tree_node p = *parent; |
| 155 | |
| 156 | (*grandparent)->right = p->left; |
| 157 | p->left = *grandparent; |
| 158 | p->right = n->left; |
| 159 | n->left = p; |
| 160 | *grandparent = n; |
| 161 | return n; |
| 162 | } |
| 163 | |
| 164 | /* Finally, deal with the case where N is a left child, but *PARENT |
| 165 | is a right child, or vice versa. */ |
| 166 | if (n == (*parent)->left) |
| 167 | { |
| 168 | (*parent)->left = n->right; |
| 169 | n->right = *parent; |
| 170 | (*grandparent)->right = n->left; |
| 171 | n->left = *grandparent; |
| 172 | *grandparent = n; |
| 173 | return n; |
| 174 | } |
| 175 | else |
| 176 | { |
| 177 | (*parent)->right = n->left; |
| 178 | n->left = *parent; |
| 179 | (*grandparent)->left = n->right; |
| 180 | n->right = *grandparent; |
| 181 | *grandparent = n; |
| 182 | return n; |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | /* Splay SP around KEY. */ |
| 187 | |
| 188 | static void |
| 189 | splay_tree_splay (sp, key) |
| 190 | splay_tree sp; |
| 191 | splay_tree_key key; |
| 192 | { |
| 193 | if (sp->root == 0) |
| 194 | return; |
| 195 | |
| 196 | splay_tree_splay_helper (sp, key, &sp->root, |
| 197 | /*grandparent=*/0, /*parent=*/0); |
| 198 | } |
| 199 | |
| 200 | /* Call FN, passing it the DATA, for every node below NODE, all of |
| 201 | which are from SP, following an in-order traversal. If FN every |
| 202 | returns a non-zero value, the iteration ceases immediately, and the |
| 203 | value is returned. Otherwise, this function returns 0. */ |
| 204 | |
| 205 | static int |
| 206 | splay_tree_foreach_helper (sp, node, fn, data) |
| 207 | splay_tree sp; |
| 208 | splay_tree_node node; |
| 209 | splay_tree_foreach_fn fn; |
| 210 | void* data; |
| 211 | { |
| 212 | int val; |
| 213 | |
| 214 | if (!node) |
| 215 | return 0; |
| 216 | |
| 217 | val = splay_tree_foreach_helper (sp, node->left, fn, data); |
| 218 | if (val) |
| 219 | return val; |
| 220 | |
| 221 | val = (*fn)(node, data); |
| 222 | if (val) |
| 223 | return val; |
| 224 | |
| 225 | return splay_tree_foreach_helper (sp, node->right, fn, data); |
| 226 | } |
| 227 | |
| 228 | /* Allocate a new splay tree, using COMPARE_FN to compare nodes, |
| 229 | DELETE_KEY_FN to deallocate keys, and DELETE_VALUE_FN to deallocate |
| 230 | values. */ |
| 231 | |
| 232 | splay_tree |
| 233 | splay_tree_new (compare_fn, delete_key_fn, delete_value_fn) |
| 234 | splay_tree_compare_fn compare_fn; |
| 235 | splay_tree_delete_key_fn delete_key_fn; |
| 236 | splay_tree_delete_value_fn delete_value_fn; |
| 237 | { |
| 238 | splay_tree sp = (splay_tree) xmalloc (sizeof (struct splay_tree_s)); |
| 239 | sp->root = 0; |
| 240 | sp->comp = compare_fn; |
| 241 | sp->delete_key = delete_key_fn; |
| 242 | sp->delete_value = delete_value_fn; |
| 243 | |
| 244 | return sp; |
| 245 | } |
| 246 | |
| 247 | /* Deallocate SP. */ |
| 248 | |
| 249 | void |
| 250 | splay_tree_delete (sp) |
| 251 | splay_tree sp; |
| 252 | { |
| 253 | splay_tree_delete_helper (sp, sp->root); |
| 254 | free ((char*) sp); |
| 255 | } |
| 256 | |
| 257 | /* Insert a new node (associating KEY with DATA) into SP. If a |
| 258 | previous node with the indicated KEY exists, its data is replaced |
| 259 | with the new value. Returns the new node. */ |
| 260 | |
| 261 | splay_tree_node |
| 262 | splay_tree_insert (sp, key, value) |
| 263 | splay_tree sp; |
| 264 | splay_tree_key key; |
| 265 | splay_tree_value value; |
| 266 | { |
| 267 | int comparison = 0; |
| 268 | |
| 269 | splay_tree_splay (sp, key); |
| 270 | |
| 271 | if (sp->root) |
| 272 | comparison = (*sp->comp)(sp->root->key, key); |
| 273 | |
| 274 | if (sp->root && comparison == 0) |
| 275 | { |
| 276 | /* If the root of the tree already has the indicated KEY, just |
| 277 | replace the value with VALUE. */ |
| 278 | if (sp->delete_value) |
| 279 | (*sp->delete_value)(sp->root->value); |
| 280 | sp->root->value = value; |
| 281 | } |
| 282 | else |
| 283 | { |
| 284 | /* Create a new node, and insert it at the root. */ |
| 285 | splay_tree_node node; |
| 286 | |
| 287 | node = (splay_tree_node) xmalloc (sizeof (struct splay_tree_node_s)); |
| 288 | node->key = key; |
| 289 | node->value = value; |
| 290 | |
| 291 | if (!sp->root) |
| 292 | node->left = node->right = 0; |
| 293 | else if (comparison < 0) |
| 294 | { |
| 295 | node->left = sp->root; |
| 296 | node->right = node->left->right; |
| 297 | node->left->right = 0; |
| 298 | } |
| 299 | else |
| 300 | { |
| 301 | node->right = sp->root; |
| 302 | node->left = node->right->left; |
| 303 | node->right->left = 0; |
| 304 | } |
| 305 | |
| 306 | sp->root = node; |
| 307 | } |
| 308 | |
| 309 | return sp->root; |
| 310 | } |
| 311 | |
| 312 | /* Remove KEY from SP. It is not an error if it did not exist. */ |
| 313 | |
| 314 | void |
| 315 | splay_tree_remove (sp, key) |
| 316 | splay_tree sp; |
| 317 | splay_tree_key key; |
| 318 | { |
| 319 | splay_tree_splay (sp, key); |
| 320 | |
| 321 | if (sp->root && (*sp->comp) (sp->root->key, key) == 0) |
| 322 | { |
| 323 | splay_tree_node left, right; |
| 324 | |
| 325 | left = sp->root->left; |
| 326 | right = sp->root->right; |
| 327 | |
| 328 | /* Delete the root node itself. */ |
| 329 | if (sp->delete_value) |
| 330 | (*sp->delete_value) (sp->root->value); |
| 331 | free (sp->root); |
| 332 | |
| 333 | /* One of the children is now the root. Doesn't matter much |
| 334 | which, so long as we preserve the properties of the tree. */ |
| 335 | if (left) |
| 336 | { |
| 337 | sp->root = left; |
| 338 | |
| 339 | /* If there was a right child as well, hang it off the |
| 340 | right-most leaf of the left child. */ |
| 341 | if (right) |
| 342 | { |
| 343 | while (left->right) |
| 344 | left = left->right; |
| 345 | left->right = right; |
| 346 | } |
| 347 | } |
| 348 | else |
| 349 | sp->root = right; |
| 350 | } |
| 351 | } |
| 352 | |
| 353 | /* Lookup KEY in SP, returning VALUE if present, and NULL |
| 354 | otherwise. */ |
| 355 | |
| 356 | splay_tree_node |
| 357 | splay_tree_lookup (sp, key) |
| 358 | splay_tree sp; |
| 359 | splay_tree_key key; |
| 360 | { |
| 361 | splay_tree_splay (sp, key); |
| 362 | |
| 363 | if (sp->root && (*sp->comp)(sp->root->key, key) == 0) |
| 364 | return sp->root; |
| 365 | else |
| 366 | return 0; |
| 367 | } |
| 368 | |
| 369 | /* Call FN, passing it the DATA, for every node in SP, following an |
| 370 | in-order traversal. If FN every returns a non-zero value, the |
| 371 | iteration ceases immediately, and the value is returned. |
| 372 | Otherwise, this function returns 0. */ |
| 373 | |
| 374 | int |
| 375 | splay_tree_foreach (sp, fn, data) |
| 376 | splay_tree sp; |
| 377 | splay_tree_foreach_fn fn; |
| 378 | void *data; |
| 379 | { |
| 380 | return splay_tree_foreach_helper (sp, sp->root, fn, data); |
| 381 | } |
| 382 | |
| 383 | /* Splay-tree comparison function, treating the keys as ints. */ |
| 384 | |
| 385 | int |
| 386 | splay_tree_compare_ints (k1, k2) |
| 387 | splay_tree_key k1; |
| 388 | splay_tree_key k2; |
| 389 | { |
| 390 | if ((int) k1 < (int) k2) |
| 391 | return -1; |
| 392 | else if ((int) k1 > (int) k2) |
| 393 | return 1; |
| 394 | else |
| 395 | return 0; |
| 396 | } |
| 397 | |
| 398 | /* Splay-tree comparison function, treating the keys as pointers. */ |
| 399 | |
| 400 | int |
| 401 | splay_tree_compare_pointers (k1, k2) |
| 402 | splay_tree_key k1; |
| 403 | splay_tree_key k2; |
| 404 | { |
| 405 | if ((char*) k1 < (char*) k2) |
| 406 | return -1; |
| 407 | else if ((char*) k1 > (char*) k2) |
| 408 | return 1; |
| 409 | else |
| 410 | return 0; |
| 411 | } |